Andrey Malimbayev

The article analyzes the spatiotemporal structure of thunderstorm activity and local electric-field changes in the Northern Tien Shan region based on data from the global WWLLN network and local measurements of the atmospheric electric field obtained by the ELIS-TS complex during 2013–2025. The main thunderstorm season from April to October is considered. During this period, the ELIS-TS complex recorded 3603 events, of which 74.6% were accompanied by negative electric-field changes and 25.4% by positive electric-field changes. Peak activity occurs from June to July, which coincides with the period of maximum convection in this region. A comparison of local measurements with WWLLN data showed that the largest number of recorded electric-field disturbances corresponded to WWLLN-detected events located within the first tens of kilometers from the station. Spatial analysis revealed an increased density of lightning discharges in mountainous and foothill areas, as well as a seasonal shift in thunderstorm activity due to the orographic influence of the terrain. Dividing the study area into lowland and mountainous zones revealed differences in the diurnal activity pattern: the peak occurs earlier in the mountains, indicating earlier convective development over high-altitude terrain.

Analysis of variations in the components of the Earth’s magnetic field, recorded at the magnetic observatory of the Institute of Ionosphere (Almaty, Kazakhstan) during the earthquakes of 22 January 2024 and 4 March 2024, showed that these fluctuations were not related to intrinsic variations in the magnetic field itself, but rather to mechanical oscillations of the magnetometer together with its support. Evidence supporting the seismokinetic origin of the variations in the vector magnetometer was the discrepancy between the total magnetic field measured by the absolute magnetometer and the total magnetic field calculated from the vector magnetometer readings. Equations were derived that relate variations in the components of the magnetic field to the tilt angles of the sensor, enabling the determination of the direction of arrival of seismic shock waves. Azimuths of earthquake epicenters were calculated from oscillations observed in magnetogram records for several events, and these were compared with azimuths obtained from a network of seismic stations. It is shown that, in order to improve the accuracy of geomagnetic field measurements—required for the study of seismoelectric and seismomagnetic phenomena, as well as for identifying earthquake precursors—the design of magnetic observatories should be supplemented with an inclinometer to enable correction of vector magnetometer measurement results.

Total electron content measurements by using dual-frequency signals of global navigation satellite systems (GNSS) makes it possible to obtain the global distribution of electron density of ionosphere with high spatial and temporal resolution. Such high spatial and temporal resolution allows to explore of small-scale traveling ionospheric disturbances generated by terrestrial geophysical events, including seismic activity, solar terminator passage, and atmospheric cyclones. One of the features of measuring the total electron content of the ionosphere with GNSS is that the measurements are made at the line of intersection of the satellite-receiver beam with the layer of maximum ionization of the ionosphere at height of ≈ 300 km. At the same time, due to the orbital motion of the satellites and the Earth rotation, the ionospheric points at which the measurements are providing carrying out a movement relative to each other, relative to the Earth and relative to the traveling ionospheric disturbances. Such a relative motion of the measurement points causes the occurrence of the Doppler effect and leads to a distortion of the wave parameters of the total electron content variations. In particular, the determination of the period of traveling ionospheric wave disturbances on the basis of time series leads to large distortions depending on the used satellite, the time and coordinates of the receiver. This paper describes a method for determining the exact wave parameters –frequency, wavelength, and propagation velocity of traveling ionospheric wave disturbances, based on the use of godochrones to analyze TEC variations. The difference between the wave parameters measured by the proposed method and from the time series of TEC data is shown on an example of wave disturbances generated by the passage of solar terminator.

The paper presents the results of a study of the behavior of ionospheric parameters of the total electron content, I(t), and electron density in the maximum F2 layer, Nm, over Almaty (Kazakhstan) [43.25° N; 76.92° E] in 1999–2013. The time interval under study covers different solar activity levels. We have shown that at F10.7>175 in summer and at F10.7>225 in winter there is a saturation effect, i.e. with increasing solar activity level values of I(t) do not increase. The observed nonlinear relationship between the total electron content of the ionosphere and the solar radiation flux F10.7 results from the nonlinear relationship between the solar ultraviolet radiation and the solar radiation flux. The study of the variability of the mid-latitude ionosphere parameters during different solar and geomagnetic activity levels has shown that the standard deviation ç(x) and average shift Xave of I(t) and Nm fluctuations relative to the quiet level weakly depend on solar activity, but greatly depend on geomagnetic activity when F10.7<100.

It is commonly accepted that two ground level enhancements of solar cosmic rays (GLEs) have so far been recorded in solar cycle 24: one on May 17, 2012, and one on January 6, 2014. The current solar...